Motor control device and motor control method

ABSTRACT

One exemplary embodiment of the present invention is a motor control device configured to control rotation of a motor based on a drive signal input from an input terminal wherein the motor control device extracts two or more pieces of information of first drive information indicating a drive state or a drive stop state of the motor, second drive information indicating a rotation direction of the motor, third drive information indicating whether the motor is in a forced stop state, and fourth drive information indicating a rotational speed of the motor from at least one of a duty ratio, a voltage, and a frequency in the single drive signal, and controls the motor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2016-109204 filed on May 31, 2016. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a motor control device and motorcontrol method for controlling a motor.

2. Description of the Related Art

A DC motor driving device of the related art is described in, forexample, Japanese Unexamined Patent Application No. 2000-316289. InJapanese Unexamined Patent Application No. 2000-316289, in the DC motordrive control device, a control state changes according to a state of anacceleration signal and a deceleration signal output from a speeddiscrimination circuit in an ASIC. Here, the control state includes“acceleration,” “neutral,” and “deceleration.”

In the motor driving device described in Japanese Unexamined PatentApplication No. 2000-316289, a signal line through which two signals, anacceleration signal and a deceleration signal, are input from the speeddiscrimination circuit in the ASIC is necessary. In addition, in themotor driving device described in Japanese Unexamined Patent ApplicationNo. 2000-316289, only acceleration, deceleration or neutral, which arestates of a rotational speed of a motor, is set using an accelerationsignal and a deceleration signal, and more signal lines are necessary inorder to determine other states.

SUMMARY OF THE INVENTION

A control device of a motor according to one exemplary embodiment of thepresent invention extracts two or more pieces of information of firstdrive information indicating a drive state or a drive stop state of themotor, second drive information indicating a rotation direction of themotor, third drive information indicating whether the motor is in aforced stop state and fourth drive information indicating a rotationalspeed of the motor from at least one of a duty ratio, a voltage, and afrequency in the single drive signal and controls the motor.

In the motor control device according to one exemplary embodiment of thepresent invention, it is possible to reduce the number of inputterminals.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a brushless DC motor and a peripheralpart thereof.

FIG. 2 is a block diagram of an example of a motor control deviceaccording to the present invention.

FIG. 3 is a diagram showing a drive signal.

FIG. 4 is a diagram showing an example of a table that is stored in astorage unit.

FIG. 5 is a flowchart describing operations of a motor control deviceaccording to the present embodiment.

FIG. 6 is a diagram showing another example of the table.

FIG. 7 is a diagram showing another example of the table.

FIG. 8 is a block diagram of another example of the motor control deviceaccording to the present invention.

FIG. 9 is a diagram showing an example of a table used in the motorcontrol device shown in FIG. 8.

FIG. 10 is an enlarged view of fourth drive information in a first rangeof the table shown in FIG. 9.

FIG. 11 is a block diagram of another example of the motor controldevice according to the present invention.

FIG. 12 is a diagram showing an example of a table used in the motorcontrol device shown in FIG. 11.

FIG. 13 is a block diagram of another example of the motor controldevice according to the present invention.

FIG. 14 is a diagram showing an example of a table used in the motorcontrol device shown in FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One exemplary embodiment of the present invention will be describedbelow with reference to the drawings. FIG. 1 is a perspective view of abrushless DC motor and a peripheral part thereof. Here, in the followingdescription, a brushless DC motor Mr will be simply referred to as amotor Mr. In addition, in the following description, as a state of themotor Mr, a drive state or a drive stop state, a rotation direction ofthe motor Mr, states of forced stop of the motor Mr and a rotationalspeed of the motor Mr may be used. The states of the motor Mr are asfollows. The drive state of the motor Mr indicates a state in whichpower is supplied to the motor Mr, and a rotation force is generated inan output shaft or a rotation force is generated. In addition, the drivestop state indicates a state in which power supply to the motor Mr isstopped and no rotation force is generated in an output shaft or norotation force is generated. In addition, the rotation direction of themotor Mr indicates a rotation direction when an output shaft Sp of themotor Mr is viewed from one side of a central axis. In the followingdescription, based on the state in FIG. 1, a counterclockwise directionwill be referred to as a CCW direction (an arrow Ar1 in FIG. 1) and aclockwise rotation direction of the output shaft Sp will be referred toas a CW direction (an arrow Ar2 in FIG. 1). Furthermore, the forced stopof the motor Mr indicates a state in which a force in a directionopposite to a rotation direction of the rotating output shaft Sp isapplied and rotation is forcibly stopped. Also, while the output shaftSp is stopped, if the state is a forced stop state, it indicates a statein which the output shaft Sp is not rotated by an external force. Therotational speed is a rotational speed of the output shaft Sp.

A motor control device A according to the present embodiment is acontrol device configured to control rotation of a brushless DC motor Mrincluded in an OA instrument such as a printer and a multifunctionmachine. Here, the motor is not limited to the brushless DC motor, butmotors capable of controlling any two or more items of control of adrive state or a drive stop state, control of a rotation direction,control of forced stop and control of a rotational speed can be widelyused. As shown in FIG. 1, the motor Mr is mounted on a metal mountingplate Ht and is mounted on a wiring board Bd of the motor control deviceA together with the mounting plate Ht. The motor Mr includes the outputshaft Sp for rotating an object.

FIG. 2 is a block diagram of an example of a motor control deviceaccording to the present invention. As shown in FIG. 1 and FIG. 2, themotor control device A includes an input terminal 1, a motor rotationcontrol circuit 2, a motor drive circuit 3, and a storage unit 4. Here,in the motor control device A according to the present embodiment, theinput terminal 1, the motor rotation control circuit 2, the motor drivecircuit 3 and the storage unit 4 are mounted on the board Bd. Inaddition, the motor control device A is connected to a power source (notshown). The motor control device A supplies power supplied from thepower source to the motor Mr and thus rotates and drives the motor Mr.

The input terminal 1 is a terminal to which a cable from a controldevice Mc included in an OA instrument is connected. In the motorcontrol device A of the present embodiment, a control signal line L1from the control device Mc is connected.

The control signal line L1 is a signal line to which a drive signal Sg1for controlling a state of a motor such as a drive state or drive stopstate, a rotation direction, forced stop and a speed is input. That is,the motor control device A controls rotation of a motor based on thedrive signal Sg1 input from the input terminal 1.

The motor rotation control circuit 2 is connected to the input terminal1. In the motor rotation control circuit 2, the drive signal Sg1 inputto the input terminal 1 is input. The motor rotation control circuit 2extracts a state of the motor Mr from the drive signal Sg1. The motorrotation control circuit 2 is a circuit including a processing circuitsuch as an MPU and a CPU. The motor rotation control circuit 2 isconnected to the storage unit 4. The storage unit 4 includes asemiconductor memory such as a ROM and a RAM. The storage unit 4 storesinformation, programs and the like necessary for drive control of themotor Mr. In this case, the motor rotation control circuit 2 accessesthe storage unit 4 and reads information, programs and the like storedin the storage unit 4.

The motor drive circuit 3 is a circuit configured to adjust power thatis supplied to the motor Mr. The motor drive circuit 3 is a circuit thatincludes, for example, a switching element, and changes a state of themotor Mr by supplying a current or stopping supply of a current to acoil (not shown) included in the motor Mr at a predetermined timing. Inthe present embodiment, the motor Mr is the brushless DC motor.

The brushless DC motor includes a plurality of coils arranged in astator. Here, any of a U phase, a V phase and a W phase is assigned tothe coils. The motor drive circuit 3 supplies a current to a U-phasecoil, a V-phase coil and a W-phase coil at a predetermined timing to seta drive state, a drive stop state, a rotation direction, a forced stopstate or the like. In addition, it is possible to change a rotationalspeed by changing a frequency at which a current is switched. Also, amotor other than the brushless DC motor may be used. In this case, themotor drive circuit 3 supplies power to a motor using a power supplymethod according to the motor.

A drive signal will be described with reference to the drawing. FIG. 3is a diagram showing a drive signal. As shown in FIG. 3, the drivesignal Sg1 is a signal in which an ON period T1 and an OFF period T2 arealternately shown. Here, in the drive signal Sg1, a percentage of the ONperiod T1 in one cycle Cy is a duty ratio Dr. The duty ratio Dr isrepresented as a percentage. For example, when there is no ON period T1in one cycle, the duty ratio Dr is “0%” and when half of one cycle isthe ON period T1, the duty ratio Dr is “50%.” Also, the control deviceMc includes a circuit capable of changing the duty ratio Dr of theoutput drive signal Sg1 from “0%” to “100%.” As a signal whose dutyratio Dr can be changed, a PWM signal can be exemplified, but thepresent invention is not limited thereto.

When the drive signal Sg1 is received from the input terminal 1, themotor rotation control circuit 2 acquires a duty ratio Dr and afrequency Fr of the drive signal Sg1. The motor rotation control circuit2 calls a table Tb1 stored in the storage unit 4 and compares the dutyratio Dr with the table Tb1. Then, the motor rotation control circuit 2extracts first drive information D1 indicating a drive state or a drivestop state of the motor Mr, second drive information D2 indicating arotation direction of the motor and third drive information D3indicating whether the motor is in a forced stop state from the dutyratio Dr. In addition, fourth drive information D4 indicating arotational speed of the motor is extracted from the frequency Fr of thedrive signal Sg1.

The table Tb1 is stored in the storage unit 4. The table Tb1 associatesthe duty ratio Dr of the drive signal Sg1 and a state of the motor Mr.FIG. 4 is a diagram showing an example of a table stored in the storageunit.

The first drive information D1, the second drive information D2, and thethird drive information D3 are Lo or Hi. In the first drive informationD1, Lo indicates a drive state of the motor Mr and Hi indicates a drivestop state of the motor Mr. In the second drive information D2, Loindicates a CCW direction, and Hi indicates a CW direction. In addition,in the third drive information D3, Lo indicates a forced stop state. Inthe following description, the forced stop state will be referred to asforced stop ON. In addition, in the third drive information D3, Hiindicates that the state is not a forced stop state. In the followingdescription, a state that is not the forced stop state will be referredto as forced stop OFF.

The table Tb1 is referred to when the first drive information D1, thesecond drive information D2 and the third drive information D3 areextracted from the duty ratio Dr. The duty ratio Dr of the drive signalSg1 may have a variation. In consideration of the variation of the dutyratio Dr, in the table Tb1, the first drive information D1, the seconddrive information D2, and the third drive information D3 are associatedwith ranges each having a width including values of the duty ratio.

In the table Tb1, the available duty ratio (from 0% to 100%) in thedrive signal Sg1 is divided into four ranges. The divided ranges of theduty ratio are set as a first range H1 to a fourth range H4. The motorcontrol device of the present embodiment stores a table in which theduty ratio is divided into a plurality of ranges and the first driveinformation D1, the second drive information D2, and the third driveinformation D3 are associated with the ranges. The table is stored inthe storage unit 4.

Accordingly, in the table Tb1, the first drive information D1, thesecond drive information D2, and the third drive information D3 areassociated with the first range H1 to the fourth range H4. Also, here,the first range H1 has a duty ratio of less than 25%. The second rangeH2 has a duty ratio of 25% or more and less than 50%. The third range H3has a duty ratio of 50% or more and less than 75%. The fourth range H4has a duty ratio of 75% or more. Also, the range of the duty ratioindicates a duty ratio of a constant width. Also, the number ofdivisions is not limited to four. For example, the duty ratio may bedivided into three or fewer ranges or divided into five or more ranges.In addition, in the table Tb1 of the present embodiment, the widths ofthe ranges of the duty ratio are equal, that is, the available dutyratio is equally divided, but the present invention is not limitedthereto. The width of the duty ratio may differ for each range.

The table Tb1 will be described in detail. In the table Tb1, the firstdrive information D1, the second drive information D2 and the thirddrive information D3 are associated with the first range H1 to thefourth range H4.

In the table Tb1, the first drive information D1, the second driveinformation D2 and the third drive information D3 associated with thefirst range H1 to the fourth range H4 are as follows. In the first rangeH1, the first drive information D1 is Lo (drive state), the second driveinformation D2 is Lo (CCW direction), and the third drive information D3is Hi (forced stop OFF). In the second range H2, the first driveinformation D1 is Hi (drive stop state), the second drive information D2is Lo (CCW direction), and the third drive information D3 is Hi (forcedstop OFF). In the third range H3, the first drive information D1 is Lo(drive state), the second drive information D2 is Hi (CW direction), andthe third drive information D3 is Hi (forced stop OFF). In the fourthrange H4, the first drive information D1 is Hi (drive stop state), thesecond drive information D2 is Hi (CW direction) and the third driveinformation D3 is Lo (forced stop ON).

In the table Tb1, the first range H1 to the fourth range H4 indicate astate of the motor Mr. The state of the motor Mr in the first range H1is forced stop OFF in a drive state in the CCW direction. The state ofthe motor Mr in the second range H2 is a drive stop state. The state ofthe motor Mr in the third range H3 is forced stop OFF in a drive statein the CW direction. The state of the motor Mr in the fourth range H4 isa forced stop ON state. As described above, the second range H2 is adrive stop state, and the fourth range H4 is forced stop ON. Therefore,in the second range H2 and the fourth range H4, the second driveinformation D2 may be Hi or Lo, that is, may be indeterminate.

Also, in the present embodiment, in order to facilitate understanding,the table Tb1 includes the term “drive state” or “drive stop state” asthe first drive information D1. In addition, the term “CCW direction” or“CW direction” is included as the second drive information D2. Inaddition, the term “forced stop ON” or “forced stop OFF” is included asthe third drive information D3. However, each piece of information ofthe table Tb1 stored in the storage unit 4 is actually Hi (1) or Lo (0).

The motor rotation control circuit 2 extracts the duty ratio Dr of thedrive signal Sg1, refers to the table Tb1 stored in the storage unit 4,and extracts the first drive information D1, the second driveinformation D2, and the third drive information D3. Then, the extractedfirst drive information D1, second drive information D2, and third driveinformation D3 are transmitted to the motor drive circuit 3 as a firstsignal S1, a second signal S2 and a third signal S3. The first signalS1, the second signal S2 and the third signal S3 each are a Hi signal ora Lo signal. Accordingly, a plurality of pieces of drive informationnecessary for driving the motor Mr can be obtained from the single drivesignal Sg1.

In addition, the motor rotation control circuit 2 acquires the frequencyFr of the drive signal Sg1. The motor rotation control circuit 2performs PLL control. The motor rotation control circuit 2 determines arotational speed of the motor Mr based on the frequency Fr of the drivesignal Sg1. That is, in the motor rotation control circuit 2, when thefrequency Fr of the drive signal Sg1 is low, a rotational speed of themotor Mr is low, and when the frequency Fr of the drive signal Sg1 ishigh, a rotational speed of the motor Mr is high. The motor rotationcontrol circuit 2 acquires the fourth drive information D4 that isinformation about a rotational speed of the motor Mr from the frequencyFr of the drive signal Sg1. Then, a clock signal Cr is generated basedon the fourth drive information D4 and transmitted to the motor drivecircuit 3.

Also, as shown in FIG. 2, the motor rotation control circuit 2 transmitsfour signals including the first signal S1, the second signal S2, thethird signal S3, and the clock signal Cr to the motor drive circuit 3independently.

The motor drive circuit 3 acquires information about a drive state or adrive stop state of the motor Mr, a rotation direction, and forced stopON or OFF from the first signal S1, the second signal S2 and the thirdsignal S3. In addition, the motor drive circuit 3 adjusts a rotationalspeed of the motor Mr based on the clock signal Cr.

A motor control device A has the above-described configuration. Next,the operation of the motor control device A will be described.

FIG. 5 is a flowchart describing operations of a motor control deviceaccording to the present embodiment. When the drive signal Sg1 is inputfrom the control device Mc through the input terminal 1 (Step S101), themotor rotation control circuit 2 acquires a duty ratio Dr and afrequency Fr of a drive signal Sg1 (Step S102).

Then, the motor rotation control circuit 2 accesses the storage unit 4and refers to the table Tb1 (Step S103). The first drive information D1,the second drive information D2, and the third drive information D3 areextracted (Step S104). The motor rotation control circuit 2 generatesthe first signal S1, the second signal S2 and the third signal S3 basedon the first drive information D1, the second drive information D2, andthe third drive information D3, generates the clock signal Cr based onthe frequency Fr, and outputs the generated signal to the motor drivecircuit 3 (Step S105).

The motor rotation control circuit 2 rotates and drives the motor Mrbased on the first signal S1, the second signal S2, the third signal S3,and the clock signal Cr (Step S106). The motor control device A in thepresent embodiment drives the motor Mr using the motor control methoddescribed above.

That is, in the motor control method of the motor control device Aaccording to the present embodiment, the first drive information D1indicating a drive state or a drive stop state of the motor Mr, thesecond drive information D2 indicating a rotation direction of the motorMr, the third drive information D3 indicating whether the motor Mr is ina forced stop state, and the fourth drive information D4 indicating arotational speed of the motor Mr are included in the single drive signalSg1. Then, two or more pieces of information of the first driveinformation D1, the second drive information D2, the third driveinformation D3, and the fourth drive information D4 are included in anyone of a duty ratio, a voltage, and a frequency of the drive signal Sg1,and two or more pieces of information of the first drive information D1,the second drive information D2, the third drive information D3 and thefourth drive information D4 are extracted from the drive signal Sg1 tocontrol the motor Mr.

The above operation will be described with reference to a specificexample. For example, in the motor control device A, the input terminal1 receives a drive signal Sg1 having a duty ratio Dr of 60% from thecontrol device Mc. In this case, the drive signal Sg1 input from theinput terminal 1 is input to the motor rotation control circuit 2. Themotor rotation control circuit 2 acquires a duty ratio Dr and afrequency Fr from the drive signal Sg1. Then, the motor rotation controlcircuit 2 accesses the storage unit 4 and refers to the table Tb1. Themotor rotation control circuit 2 checks which of the first range H1 tothe fourth range H4 includes 60%, which is the duty ratio Dr of thedrive signal Sg1. Here, since the duty ratio Dr is 60%, the duty ratioDr of the drive signal Sg1 is in the third range H3.

The motor rotation control circuit 2 extracts the first driveinformation D1, the second drive information D2, and the third driveinformation D3 in the third range H3 from the table Tb1. Here, the firstdrive information D1 is in a drive state, that is, Lo. The second driveinformation D2 is a CW direction (Hi). The third drive information D3 isforced stop OFF (Hi). Accordingly, the motor rotation control circuit 2determines that the drive signal Sg1 is a command signal for setting themotor Mr in a drive state and a CW direction. Therefore, the motorrotation control circuit 2 transmits a Lo signal as the first signal S1based on the first drive information D1, a Hi signal as the secondsignal S2 based on the second drive information D2, and a Hi signal asthe third signal S3 based on the third drive information D3 to the motordrive circuit 3 at the same time.

In addition, the motor rotation control circuit 2 generates a clocksignal Cr indicating a rotational speed of the motor Mr from thefrequency Fr of the drive signal Sg1. The motor rotation control circuit2 transmits the clock signal Cr and the first signal S1, the secondsignal S2, and the third signal S3 to the motor drive circuit 3 at thesame time.

The motor drive circuit 3 supplies power for setting the motor Mr in aCW direction and a drive state to the motor Mr based on the first signalS1, the second signal S2, and the third signal S3. Also, power supply tothe motor Mr may be performed by switching a switching element (notshown) along a power line (not shown) connected to a power source (notshown). However, a method of supplying power to the motor Mr is notlimited thereto.

In the motor control device A using the motor control method accordingto the present embodiment, the first drive information D1, the seconddrive information D2, and the third drive information D3 are extractedfrom the duty ratio of the single drive signal Sg1 from the controldevice Mc that is an external device. In addition, the fourth driveinformation D4 is extracted from the frequency of the drive signal Sg1.Accordingly, in the single drive signal Sg1, the first drive informationD1, the second drive information D2, and the third drive information D3can be extracted from the duty ratio, and the fourth drive informationD4 can be extracted from the frequency. Therefore, it is possible toselect an element of an accurate input signal for each piece of driveinformation to be extracted.

In the motor control device A according to the present embodiment, it ispossible to extract a plurality of pieces of drive information of themotor Mr from the single drive signal Sg1 from an external device.Therefore, one terminal can be set to be allocated to the drive signalSg1 of the input terminal 1. In addition, since information itemsincluded in the drive signal Sg1 can be extracted at the same time, itis possible to minimize a delay time until all information is extractedcompared to a configuration in which a single signal is divided in timeseries and a plurality of pieces of information are transmitted. Inaddition, compared to when a single signal is divided in time series, itis possible to simplify an information extraction operation, and it ispossible to simplify a circuit configuration of the motor rotationcontrol circuit 2. As a result, it is possible to reduce a load of themotor rotation control circuit 2.

In addition, in the table Tb1, a range (the second range H2) indicatinga drive stop state of the first drive information D1 is included betweena range (the first range H1) indicating rotation in a first direction(CCW direction) of the second drive information D2 and a range (thethird range H3) indicating rotation in a second direction (CW direction)that is a direction opposite to the first direction of the second driveinformation D2. In this manner, in the table Tb, the second range H2indicating a drive stop state is included between the first range H1 ofa drive state of the motor Mr in the CCW direction and the third rangeH3 in the drive state in the CW direction. When the duty ratio Dr of thedrive signal Sg1 changes, the drive state in the first direction isprevented from being immediately switched to the drive state in thesecond direction so that it is possible to reduce a load of the motorMr.

In addition, in the table Tb1, a range (the third range H3) indicatingrotation in the second direction (CW direction) that is a directionopposite to the first direction of the second drive information D2 isincluded between a range (the first range H1) indicating rotation in thefirst direction (CCW direction) of the second drive information D2 and arange (the fourth range H4) indicating a forced stop state of the thirddrive information D3. In such a configuration, it is possible to quicklyand forcibly stop the motor Mr that rotates in the CW direction. Also,in the present embodiment, the second drive information D2 in the firstrange H1 is the CCW direction, and the second drive information D2 inthe third range H3 is the CW direction, or vice versa. In this case,when the table Tb1 is used, it is possible to quickly and forcibly stopthe motor Mr that rotates in the CCW direction. In addition, while thefourth range H4 is a range in which the duty ratio is the highest, thepresent invention is not limited thereto. For example, a portion of thefirst range H1 may be set as a range in which the third driveinformation D3 is forced stop ON.

A modification of a motor control device according to a first embodimentwill be described. FIG. 6 is a diagram showing another example of thetable. In a table Tb2 in FIG. 6, available values of the duty ratio aredivided into five equal ranges. Therefore, in the table Tb2, a fifthrange H5 has a duty ratio of less than 20%. The first range H1 has aduty ratio of 20% or more and less than 40%. The second range H2 has aduty ratio of 40% or more and less than 60%. The third range H3 has aduty ratio of 60% or more and less than 80%. The fourth range H4 has aduty ratio of 80% or more.

The table Tb2 has the same configuration as the table Tb1 except thatboundaries of the duty ratio of the first range H1 to the fourth rangeH4 are different. Therefore, detailed description of the first range H1to the fourth range H4 will be omitted. In the table Tb2, the firstdrive information D1, the second drive information D2, and the thirddrive information D3 associated with the fifth range H5 are the same asthose of the fourth range H4. In the fifth range H5, the first driveinformation D1 is Hi (drive stop state), the second drive information D2is Hi (CW direction), and the third drive information D3 is Lo (forcedstop ON). The fifth range H5 is forced stop ON.

That is, in the table Tb2, a range (the first range H1) indicatingrotation in the first direction (CCW direction) that is a directionopposite to the second direction of the second drive information D2 isincluded between a range (the third range H3) indicating rotation in thesecond direction (CW direction) of the second drive information D2 and arange (the fifth range H5) indicating a forced stop state of the thirddrive information D3. In such a configuration, even if the motor Mr isin a rotation state in the CCW direction or in a rotation state in theCW direction, it is possible to directly forcibly stop the motor Mr bychanging the duty ratio. Accordingly, even if a problem occurs, it ispossible to quickly stop the motor Mr.

Another modification of the motor control device according to the firstembodiment will be described. FIG. 7 is a diagram showing anotherexample of the table. In a table Tb3 in FIG. 7, a boundary range H6 isincluded in a portion that is adjacent to the first range H1 and thesecond range H2. In the table Tb3, the first range H1 has a duty ratioof less than 24% and the second range H2 has a duty ratio of 26% or moreand less than 49%. Also, boundary ranges H6 are provided in a portionthat is adjacent to the second range H2 and the third range H3, and aportion that is adjacent to the third range H3 and the fourth range H4.That is, in the table Tb3, the boundary ranges H6 are included inboundaries between adjacent ranges.

In the table Tb3, the boundary ranges H6 are provided in portions thatare adjacent to ranges associated with the first drive information D1,the second drive information D2, and the third drive information D3. Theboundary ranges H6 are dead zones that are used in hysteresis control.Therefore, when the duty ratio Dr changes and is in a boundary range H6,the motor rotation control circuit 2 extracts information associatedwith a range in which the duty ratio Dr before change is included.

For example, an example in which the duty ratio Dr changes between 23%and 27% will be described. When the duty ratio Dr is 23%, the motorrotation control circuit 2 determines that the duty ratio Dr is thefirst range H1. In this state, when the duty ratio Dr changes and is25%, it is in the boundary range H6. Since the duty ratio Dr enters theboundary range H6 from the first range H1, the motor rotation controlcircuit 2 extracts drive information of the first range H1 successivelyfrom the previous range.

Then, when the duty ratio Dr exceeds 26%, the motor rotation controlcircuit 2 determines that the duty ratio Dr is in the second range H2.On the other hand, it is assumed that the duty ratio Dr is changed from27% to 25%. Since the duty ratio Dr enters the boundary range H6 fromthe second range H2, the motor rotation control circuit 2 extracts driveinformation of the second range H2 successively from the previous range.Therefore, when the duty ratio Dr is less than 24%, the motor rotationcontrol circuit 2 determines that the duty ratio Dr is in the firstrange H1.

When a boundary range is provided between ranges with which the firstdrive information D1, the second drive information D2 and third driveinformation are associated and the duty ratio Dr is in the boundaryrange, drive information in the previous range is extracted. As aresult, it is possible to prevent drive information from beingfrequently switched even if the duty ratio Dr changes to a value in thevicinity of the boundary.

Also, while all widths (hystereses) of the boundary ranges betweenadjacent ranges are 2% in the present embodiment, the present inventionis not limited thereto. For example, the width of the boundary range maybe greater or smaller than 2%. When the width of the boundary rangeincreases, the control is stable, but detection accuracy of switching ofthe state of the motor Mr decreases. In addition, when the width of theboundary range decreases, the state of the motor Mr is easily switched,but the control is likely to be unstable. Therefore, it is possible tochange the width of the boundary range in response to deterioration ofsignal transmission and a noise imparted state in the motor controldevice A, the control device Mc, and wirings connecting them.

In addition, while all widths of the boundary ranges between adjacentranges are 2%, the present invention is not limited thereto. Forexample, the forced stop state may be a forced stop state due to aproblem. Therefore, in order to restore the state from the forced stopstate, a greater hysteresis is given, that is, the width of the boundaryrange between the third range H3 and the fourth range H4 may be 4%.

A motor control device according to an exemplary second embodiment ofthe present invention will be described with reference to the drawing.FIG. 8 is a block diagram of another example of the motor control deviceaccording to the present invention. Here, a motor control device B ofthe present embodiment is the same as the motor control device A of thefirst embodiment except that a motor rotation control circuit 2 b isdifferent and a table Tb4 is different. Accordingly, parts that aresubstantially the same will not be described in detail.

The motor rotation control circuit 2 b of the motor control device B inthe present embodiment is a circuit configured to acquire a duty ratioDr from the drive signal Sg1. The fourth drive information D4 that isinformation about a rotational speed is extracted from the duty ratio Dracquired from the drive signal Sg1 in addition to the first driveinformation D1, the second drive information D2, and the third driveinformation D3. Then, the motor rotation control circuit 2 b transmits afourth signal S4 to the motor drive circuit 3 in place of the clocksignal Cr.

That is, a motor control device B extracts at least two pieces ofinformation of the first drive information D1, the second driveinformation D2, the third drive information D3, and the fourth driveinformation D4 from the duty ratio Dr of the drive signal Sg1.

In the motor control device B, the motor rotation control circuit 2 bacquires the duty ratio Dr of the drive signal Sg1, refers to the tableTb4 stored in the storage unit 4, and extracts drive information.

Here, the table Tb4 will be described. FIG. 9 is a diagram showing anexample of a table used in the motor control device shown in FIG. 8. Thetable Tb4 has a configuration in which the fourth drive information D4is added to the table Tb1. In addition, FIG. 10 is an enlarged view ofthe fourth drive information D4 of the first range of the table shown inFIG. 9. Also, while FIG. 10 shows the fourth drive information D4 of thefirst range H1, the third range H3 also has the same configuration.

As shown in FIG. 9, in the table Tb4, the range of the duty ratio isdivided into the first range H1, the second range H2, the third rangeH3, and the fourth range H4. Since these ranges, and the first driveinformation D1, the second drive information D2, and the third driveinformation D3 are the same as those in the table Tb1, details thereofwill be omitted.

Here, the first range H1 of the table Tb4 is focused on. In the tableTb4, the duty ratio Dr and the fourth drive information D4 areassociated. The fourth drive information D4 of the first range H1 isdivided into 25 levels of 1% from 0% to 24% of the duty ratio. Differentrotational speeds are associated with the divided levels. Also, here, arotational speed associated with a level of a duty ratio of 0% is set asR1 and a rotational speed associated with a level of a duty ratio of 24%is set as R25. Here, R1<R25 is assumed. For example, a speed when theduty ratio Dr of the drive signal Sg1 is 16% is set as R16. The thirdrange H3 is similarly divided into 25 levels, a rotational speedassociated with a level of a duty ratio of 50% is set as R1, and arotational speed associated with a duty ratio of 74% is set as R25.

For example, the motor rotation control circuit 2 b acquires 15% as theduty ratio Dr of the drive signal Sg1. In this case, since the dutyratio Dr is in the first range H1, a drive state (Lo) is extracted asthe first drive information D1 of the first range H1. In addition, theCCW direction (Lo) is extracted as the second drive information D2. Inaddition, forced stop OFF (Hi) information is extracted as the thirddrive information D3. In addition, the motor rotation control circuit 2b extracts a rotational speed R16 when the duty ratio Dr is 15% based onthe table Tb4.

Then, the motor rotation control circuit 2 b transmits Lo, Lo, and Hisignals to the motor drive circuit 3 as the first signal S1, the secondsignal S2, and the third signal S3. In addition, as the fourth signalS4, a signal including information of the rotational speed R16 istransmitted to the motor drive circuit 3.

As described above, in the motor control device B, information items ofthe first drive information D1, the second drive information D2, thethird drive information D3, and the fourth drive information D4 can beextracted from the duty ratio Dr of the drive signal Sg1. Accordingly,it is possible to control a drive state and a rotational speed of themotor Mr for which PLL control is difficult. Also, when the motor Mr hasthe same configuration as in the first embodiment, the fourth signal S4is set as a signal having the same configuration as the clock signal Crand may be transmitted to the motor drive circuit 3.

A modification of the motor control device according to the secondembodiment will be described. FIG. 11 is a block diagram of anotherexample of the motor control device according to the present invention.Here, a motor control device C of the present embodiment is the same asthe motor control device B of the second embodiment except that a motorrotation control circuit 2 c is different and a table Tb5 is different.Accordingly, parts that are substantially the same will not be describedin detail.

The motor rotation control circuit 2 c of the motor control device C inthe present embodiment is a circuit configured to acquire a voltage Vrfrom the drive signal Sg1. The fourth drive information D4 that isinformation about a rotational speed is extracted from the voltage Vracquired from the drive signal Sg1 in addition to the first driveinformation D1, the second drive information D2, and the third driveinformation D3. Here, since a circuit configured to acquire a voltage ofan input signal has already been described, details thereof will beomitted.

The motor control device C extracts at least two pieces of informationof the first drive information D1, the second drive information D2, thethird drive information D3, and the fourth drive information D4 from thevoltage Vr of the drive signal Sg1.

In the motor control device C, the motor rotation control circuit 2 cacquires the voltage Vr of the drive signal Sg1, refers to the table Tb5stored in the storage unit 4, and extracts drive information.

Here, the table Tb5 will be described. FIG. 12 is a diagram showing anexample of a table used in the motor control device shown in FIG. 11. Inthe table Tb5, the range of the available voltage, for example, Vr1 toVr5, of the drive signal Sg1 is divided into four equal ranges. Thedivided voltage ranges are set as a first range I1 to a fourth range I4.The first range I1 is a range in which the voltage is Vr1 or higher andlower than Vr2. The second range I2 is a range in which the voltage isVr2 or higher and lower than Vr3. The third range I3 is a range in whichthe voltage is Vr3 or higher and lower than Vr4. The fourth range I4 isa range in which the voltage is Vr4 or higher and Vr5 or less.

Also, the first drive information D1, the second drive information D2,the third drive information D3, and the fourth drive information D4 inthe first range I1 to the fourth range I4 in the table Tb5 aresubstantially the same as the first drive information D1, the seconddrive information D2, the third drive information D3, and the fourthdrive information D4 in the first range H1 to the fourth range H4 of thetable Tb4. Accordingly, details thereof will not be described. Also,depending on the range of the available voltage of the drive signal Sg1,it may be difficult for the first range I1 and the third range I3 to bedivided into 25 levels. In this case, the first range I1 and the thirdrange I3 are divided into 25 or fewer levels, for example, 10 levels,and a speed may be associated with each level.

In such a configuration, a signal whose duty ratio is not easilydetected can be used as a drive signal for driving the motor Mr using asignal having a different voltage. Here, the voltage is, for example, apeak voltage. However, a physical quantity defined as the voltage is notlimited thereto. For example, an integral value of a voltage value maybe used and an average value may be used.

Another modification of the motor control device according to the secondembodiment will be described. FIG. 13 is a block diagram of anotherexample of the motor control device according to the present invention.Here, a motor control device D of the present embodiment is the same asthe motor control device B of the second embodiment except that a motorrotation control circuit 2 d is different and a table Tb6 is different.Accordingly, parts that are substantially the same will not be describedin detail.

The motor rotation control circuit 2 d of the motor control device Dshown in the present embodiment is a circuit configured to acquire afrequency Fr from the drive signal Sg1. The fourth drive information D4that is information about a rotational speed is extracted from thefrequency Fr acquired from the drive signal Sg1 in addition to the firstdrive information D1, the second drive information D2, and the thirddrive information D3. Here, since a circuit configured to acquire afrequency of an input signal has already been described, details thereofwill be omitted.

The motor control device D extracts at least two pieces of informationof the first drive information D1, the second drive information D2, thethird drive information D3, and the fourth drive information D4 from thefrequency Fr of the drive signal Sg1.

In the motor control device D, the motor rotation control circuit 2 dacquires the frequency Fr of the drive signal Sg1, refers to the tableTb6 stored in the storage unit 4, and extracts drive information.

Here, the table Tb6 will be described. FIG. 14 is a diagram showing anexample of a table used in the motor control device shown in FIG. 13. Inthe table Tb6, the range of the available frequency, for example, Fr1 toFr5, of the drive signal Sg1 is divided into four equal ranges. Thedivided frequency ranges are set as a first range J1 to a fourth rangeJ4. The first range J1 is a range in which the frequency is Fr1 orhigher and lower than Fr2. The second range J2 is a range in which thefrequency is Fr2 or higher and lower than Fr3. The third range J3 is arange in which the frequency is Fr3 or higher and lower than Fr4. Thefourth range J4 is a range in which the frequency is Fr4 or higher andFr5 or lower.

Also, the first drive information D1, the second drive information D2,the third drive information D3 and the fourth drive information D4 inthe first range J1 to the fourth range J4 in the table Tb6 aresubstantially the same as the first drive information D1, the seconddrive information D2, the third drive information D3, and the fourthdrive information D4 in the first range H1 to the fourth range H4 in thetable Tb4. Accordingly, details thereof will not be described. Also,depending on the range of the available frequency of the drive signalSg1, it may be difficult for the first range J1 and the third range J3to be divided into 25 levels. In this case, the first range J1 and thethird range J3 are divided into 25 or fewer levels, for example, 10levels, and a speed may be associated with each level.

In such a configuration, a signal whose duty ratio is not easilydetected can be used as a drive signal for driving the motor Mr using adrive signal having a different frequency.

In addition, the first drive information D1, the second driveinformation D2, the third drive information D3, and the fourth driveinformation D4 may be extracted using a duty ratio and a voltage of thedrive signal Sg1. In addition, the first drive information D1, thesecond drive information D2, the third drive information D3, and thefourth drive information D4 may be extracted using a voltage and afrequency of the drive signal Sg1.

The motor control device according to one exemplary embodiment of thepresent invention can extract two or more pieces of information of thefirst drive information D1 indicating a drive state or drive stop stateof the motor, the second drive information D2 indicating a rotationdirection of the motor, the third drive information D3 indicatingwhether the motor is in a forced stop state, and the fourth driveinformation D4 indicating a rotational speed of the motor from at leastone of the duty ratio Dr, the voltage Vr, and the frequency Fr in thesingle drive signal Sg1 input from the input terminal 1, and control themotor Mr.

Here, as the drive state of the motor Mr, the first drive information D1indicating a drive state or a drive stop state of the motor, the seconddrive information D2 indicating a rotation direction of the motor, thethird drive information D3 indicating whether the motor is in a forcedstop state, and the fourth drive information D4 indicating a rotationalspeed of the motor may be exemplified, but the present invention is notlimited thereto. In addition, information used when the motor Mr drives,for example, a feedback gain and information indicating whether softstart is performed can be widely used. In this case, it is possible torespond to such a case by increasing the number of divisions in a table.In addition, each piece of drive information may be extracted using aplurality of tables.

The tables in the above embodiments and modifications are tables inwhich values acquired from the drive signal Sg1, that is, the duty ratioDr, the voltage Vr, and the frequency Fr, are associated with driveinformation items, but the present invention is not limited thereto. Forexample, the table may have a form of graph showing relationshipsbetween values acquired from the drive signal Sg1 and drive informationitems. In addition, drive information may be extracted according tocalculation using an arithmetic expression showing relationships betweenvalues acquired from the drive signal Sg1 and drive information items.That is, while the motor control device has a configuration in which themotor rotation control circuit refers to the table, the presentinvention is not limited thereto. A configuration or a method in whichthe motor rotation control circuit can uniquely extract driveinformation items from values acquired from the drive signal Sg1 can bewidely used.

While the above embodiments have a configuration in which the motorrotation control circuit 2 and the motor drive circuit 3 are separatecircuits and mounted on the board Bd, the present invention is notlimited thereto. For example, the motor rotation control circuit 2 andthe motor drive circuit 3 may be integrated into one package, that is,one chip. In this manner, it is possible to remove a signal line due tointegration into one chip. In addition, at least one of the motorrotation control circuit 2 and the motor drive circuit 3 may be aprogram that operates in an arithmetic processing circuit. In this case,the program may be stored in the storage unit 4.

The motor control device according to the exemplary embodiment of thepresent invention extracts two or more pieces of information of firstdrive information indicating a drive state or a drive stop state of themotor, second drive information indicating a rotation direction of themotor, third drive information indicating a forced stop state of themotor, and fourth drive information indicating a rotational speed of themotor from a single drive signal from an external device (here, thecontrol device Mc). Therefore, it is possible to reduce the number ofinput terminals, and it is possible to reduce the size of the motorcontrol device. In addition, since it is possible to reduce the numberof constituent members of the motor control device, it is possible toreduce cost.

While exemplary embodiments of the present invention have been describedabove, various modifications of the embodiments can be made within thespirit and scope of the present invention.

The present invention can be used as a motor control device configuredto drive a motor that is arranged inside an OA instrument such as aprinter and a multifunction machine. The present invention can also beused in various electronic devices in addition to the printer and themultifunction machine.

Features of the above-described preferred embodiments and themodifications thereof may be combined appropriately as long as noconflict arises.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A motor control device configured to controlrotation of a motor based on a single drive signal input from an inputterminal, wherein the motor control device stores a table in which atleast one of a duty ratio, a voltage, and a frequency in the singledrive signal is divided into a plurality of ranges; the motor controldevice extracts two or more pieces of information including first driveinformation indicating a drive state or a drive stop state of the motor,second drive information indicating a rotation direction of the motor,third drive information indicating whether the motor is in a forced stopstate, and fourth drive information indicating a rotational speed of themotor from the at least one of the duty ratio, the voltage, and thefrequency in the single drive signal, and controls the motor accordingto the extracted two or more pieces of information; in the table, aboundary range which has no drive signal is included in a boundarybetween adjacent ranges associated with the first drive information, thesecond drive information, and the third drive information; and when theat least one of the duty ratio, the voltage, and the frequency in thesingle drive signal changes and is in the boundary range, informationassociated with a range including the at least one of the duty ratio,the voltage, and the frequency in the single drive signal beforechanging is extracted.
 2. The motor control device according to claim 1,wherein at least two pieces of information of the first driveinformation, the second drive information, the third drive information,and the fourth drive information are extracted from the duty ratio ofdrive signal.
 3. The motor control device according to claim 1, whereinat least two pieces of information of the first drive information, thesecond drive information, the third drive information, and the fourthdrive information are extracted from the voltage of the drive signal. 4.The motor control device according to claim 1, wherein at least twopieces of information of the first drive information, the second driveinformation, the third drive information, and the fourth driveinformation are extracted from the frequency of the drive signal.
 5. Themotor control device according to claim 1, wherein the first driveinformation, the second drive information, and the third driveinformation are extracted from the duty ratio of the drive signal, andwherein the fourth drive information is extracted from the frequency ofthe drive signal.
 6. The motor control device according to claim 5,wherein the motor control device refers to the table and extracts thefirst drive information, the second drive information, and the thirddrive information.
 7. The motor control device according to claim 6,wherein, in the table, a range indicating a drive stop state of thefirst drive information is included between a range indicating rotationin a first direction of the second drive information and a rangeindicating rotation in a second direction that is a direction oppositeto the first direction of the second drive information.
 8. The motorcontrol device according to claim 6, wherein, in the table, a rangeindicating rotation in a second direction that is a direction oppositeto a first direction of the second drive information is included betweena range indicating rotation in the first direction of the second driveinformation and a range indicating a forced stop state of the thirddrive information.
 9. The motor control device according to claim 8,wherein, in the table, a range indicating rotation in the firstdirection that is a direction opposite to the second direction of thesecond drive information is included between a range indicating rotationin the second direction of the second drive information and a rangeindicating a forced stop state of the third drive information.
 10. Amotor control method through which drive of a motor is controlled basedon a drive signal, comprising: storing a table in which at least one ofa duty ratio, a voltage, and a frequency in the single drive signal isdivided into a plurality of ranges; wherein first drive informationindicating a drive state or a drive stop state of the motor, seconddrive information indicating a rotation direction of the motor, thirddrive information indicating whether the motor is in a forced stopstate, and fourth drive information indicating a rotational speed of themotor are included in the single drive signal, two or more pieces ofinformation of the first drive information, the second driveinformation, the third drive information, and the fourth driveinformation are included in the at least one of the duty ratio, thevoltage, and the frequency of the drive signal, and two or more piecesof information of the first drive information, the second driveinformation, the third drive information, and the fourth driveinformation are extracted from the drive signal to control the motoraccording to the extracted two or more pieces of information; in thetable, a boundary range which has no drive signal is included in aboundary between adjacent ranges associated with the first driveinformation, the second drive information, and the third driveinformation; and when the at least one of the duty ratio, the voltage,and the frequency in the single drive signal changes and is in theboundary range, information associated with a range including the atleast one of the duty ratio, the voltage, and the frequency in thesingle drive signal before changing is extracted.
 11. The motor controlmethod according to claim 10, wherein the first drive information, thesecond drive information, and the third drive information are extractedfrom the duty ratio of the drive signal, and the fourth driveinformation is extracted from the frequency of the drive signal.
 12. Themotor control method according to claim 11, wherein an additional tablein which the duty ratio is divided into a plurality of ranges and thefirst drive information, the second drive information, and the thirddrive information are associated with the ranges is used in controllingthe motor, and the first drive information, the second driveinformation, and the third drive information are extracted.